It has been well known that dye images are produced by subjecting a light-sensitive silver halide color photographic material (hereinafter "color photographic material") to imagewise exposure to effect color development, whereby an oxidized product of an aromatic primary amine type color developing agent couples with a coupler to form dyes including, for example, indophenol, indoaniline, indamine, azomethine, phenoxadine, phenadine and other dyes similar to these. In such a photographic system, generally employed is a color reproduction system utilizing the subtractive color process, in which used is a color photographic material comprising blue-sensitive, green-sensitive and red-sensitive silver halide emulsion layers containing couplers each having the relationship of complementary color, namely, couplers which color-develop in yellow, magenta and cyan, respectively.
The coupler used for formation of yellow color images includes, for example, acetoanilide type couplers, and, as the coupler for formation of magenta color images, for example, pyrazolone, pyrazolobenzimidazole, pyrazolotriazole or indazolone type couplers are known, and further, as the coupler for formation of cyan color images, for example, phenol or naphthol type couplers are generally used.
The dye images thus obtained are desired not to undergo any color change or color-fading even when exposed to light for a long period of time or preserved under the conditions of high temperature and high humidity. Also desired are those in which non-image portions of a color photographic material may not yellow by light, moisture or heat.
However, in the case of magenta couplers, yellow stain (or Y-stain) by light, at an non-image portion and color-fading by light, at a dye image portion are very largely caused as compared with those in the case of yellow couplers or cyan couplers, to often raise problems.
The coupler widely used for formation of magenta dye includes, for example, 1,2-pyrazol-5-on type couplers. It has been a serious problem that the magenta couplers of 1,2-pyrazol-5-on type have a secondary absorption at the vicinity of 430 nm in addition to a primary absorption at the vicinity of 550 nm, and therefore various studies have been made to solve such a problem.
A magenta coupler having an anilino group at the 3-position of the 1,2-pyrazol-5-on type coupler, which is small in the above-mentioned secondary absorption, is useful for obtaining, in particular, a color image for printing. This art is disclosed, for example, in U.S. Pat. No. 2,343,703, British Patent No. 1,059,994, etc.
However, the above magenta couplers have a disadvantage that they are extremely poor in the image stability, in particular, the fastness to light of dye images, to suffer from Y-stain at a non-image portion.
As a means for decreasing the secondary absorption at the vicinity of 430 nm of the above magenta coupler, there have been proposed magenta couplers including, for example, pyrazolobenzimidazoles disclosed in British Patent No. 1,047,612, indazolones disclosed in U.S. Pat. No. 3,770,447, and pyrazolotriazoles disclosed in U.S. Pat. No. 3,725,067, British Patent Nos. 1,252,418 and 1,334,515, Japanese Unexamined Patent Publications No. 162548/1984 and No. 171956/1984, etc. The dyes formed through these couplers shows extremely smaller secondary absorption at the vicinity of 430 nm than the dyes formed through the 1,2-pyrazol-5-on type coupler do, and thus, they are desirable from the viewpoint of the color reproducibility, and also they are advantageous in that they are desirably very little liable to generation of Y-stain at a non-image portion against light, heat and humidity.
However, in general, the azomethine dye to be formed through the magenta couplers of pyrazolotriazole type have very low fastness to light to seriously damage the performances of a color photographic material, in particular, a color photographic material for print, and therefore have not put into practical use in color photographic materials for print.
Japanese Unexamined Patent Publication also proposes a technique for improving the fastness to light of a magenta dye image obtained from 1H-pyrazolo-[3,2-C]-s-triazole type magenta coupler by using 1H-pyrazolo-[3,2-C]-s-triazole type magenta coupler in combination with a phenol type compound or a phenol ether type compound. However, even in the above technique, some are not only insufficient for preventing the color-fading of the above magenta dye image against light, but also accelerate the color-fading by light on the contrary.
In short, there has not been found any means for sufficiently improving the fastness to light when the above pyrazolotriazole type magenta couplers are used, and an improvement has been earnestly sought after.